Flavour enhancers enhance the existing flavour of a food product. Two classes of well-known flavour enhancing compounds are monosodium glutamate and 5'-ribonucleotides. These flavour enhancing compounds are used as such, but are also, separately or in combination, part of flavour enhancing compositions.
Yeast extracts, for instance, which are prepared by enzymatic degradation of yeast, contain the flavour enhancing 5'-ribonucleotides guanosine-5'-monophosphate (5'-GMP) and inosine-5'-monophosphate (5'-IMP).
Hydrolysed vegetable proteins (HVPs), which are prepared by acid or enzymatic hydrolysis of vegetable protein, typically contain monosodium glutamate as their flavour enhancing compound. This monosodium glutamate is derived from the amino acids glutamic acid and glutamine released from the protein during hydrolysis.
Flavour enhancers which do not contain substantial amounts of at least either of the two classes of flavour enhancing compounds are very scarce. As far as the inventors know, the only disclosure of a flavour enhancer of this type is in U.S. Pat. No. 5,077,062.
U.S. Pat. No. 5,077,062 describes a soy hydrolysate which is prepared by hydrolysing at pH 6.6-7.2, 30-38.degree. C. for about two hours. The resulting hydrolysate contains no free amino acids, is low in glutamate, and can be used as a flavour enhancer. However, the described flavour enhancer enhances fish flavours only.